Bilateral Keratitis Caused By Stenotrophomona Maltophilia In A Baseline Epitheliopathy

Infectious keratitis caused by Stenotrophomonas maltophilia is an uncommon opportunistic infection followed by instability of the ocular surface and immunodeficiency disorders. Due to its low incidence, there is an absence of a standardized treatment protocol and the evidence is derived only from case reviews. Therefore our objective is to describe the clinical features and manegement of Stenotrophomonas maltophilia keratitis trough a case treated at our center.

Department of Ophthalmology, Hospital Son Llàtzer, Palma, Spain.

A 53-year-old man, non-contact lens (CL) user with chronic alcoholism, presented to our hospital with bilateral painless visual disturbances persisting for a month. Despite no prior corneal surgeries, recent treatment included topical corticosteroids and therapeutic CL. Clinical examination showed hand motion (HM) visual acuity (VA) in the right eye and 0.05 in the left eye. Slit-lamp examination revealed rapid progression from wave-like epitheliopathy to corneal ulcer and dense central stromal infiltrates in both eyes, with a 1mm left eye hypopyon. Initial treatment included topical vancomycin, tobramycin, atropine and intravenous ciprofloxacin. Bacterial culture confirmed S.maltophilia and co-infection with S.aureus and S.liquefaciens. 

Based on susceptibility test results, the patient received alternating topical levofloxacin and vancomycin every two hours, along with tobramycin and medroxyprogesterone. The patient's clinical condition steadily improved, with the hypopyon resolving within 2 days and the infiltrate clearing within four weeks of treatment initiation. Despite challenges in corneal epithelium healing, sustained treatment with dexamethasone, medroxyprogesterone, insulin eye drops, and autologous serum resolved the epithelium defect. Moreover, two amniotic membrane transplants were performed to control inflammation and stimulate epithelium regeneration.

The patient's VA improved from HM to 0.1, despite the presence of corneal leukomas and cataracts in both eyes.

In this case, the concurrent use of corticosteroids with a corneal defect is a potential risk for Stenotrophomonas infection. Our investigations, including serological, autoimmune, and imaging studies, found no abnormalities. However, alcoholism, an immunosuppressive factor, may also contribute to susceptibility.

Finally, the severity of our case may stem from a multi-pathogenic infection, known for poorer outcomes compared to mono-pathogenic infections in S. maltophilia-associated ocular infections, as indicated by previous studies.